Influenza

Influenza (also hergab in Somali) is an acute infectious disease affecting the respiratory tract—the nose, throat, and sometimes the lungs. It is caused by a virus (a microscopic organism not visible to the naked eye) called the influenza virus. The disease begins abruptly and causes fever, headache, muscle aches, fatigue, loss of appetite, and a harsh cough.

Influenza typically resolves within one to two weeks without specific treatment. However, certain groups—young children, elderly people, pregnant women, and those with chronic conditions such as asthma, diabetes, or heart disease—are at risk of developing serious complications such as pneumonia.

Cause and viral types

Influenza viruses are classified into four major types: A, B, C, and D. Types A and B infect humans during epidemic seasons. Type A also lives in birds and certain animals and has the potential to cause pandemics. Type A viruses are further divided into subtypes based on two proteins on the viral surface called hemagglutinin (H) and neuraminidase (N), such as H1N1 and H3N2.

The influenza virus changes constantly. Minor changes occurring each year (antigenic drift) can allow the body's previous immune response to be incomplete, necessitating updated vaccines. Major genetic changes (antigenic shift), which occur when two different viruses exchange genetic material, can lead to pandemics.

Transmission

The virus spreads through tiny droplets in the air released when an infected person coughs, sneezes, or speaks. It can also spread when contaminated hands touch the nose, mouth, or eyes. The incubation period—from viral acquisition to symptom onset—is one to four days. An infected person can transmit the virus one day before symptoms appear and for several days after.

Prevention and treatment

Influenza vaccination is the most effective prevention method; it is recommended annually because the virus changes. Other measures include regular handwashing, covering the mouth when coughing, and keeping sick people at home. Treatment is mainly supportive: rest, fluids, and fever-reducing medications. Antiviral drugs such as oseltamivir are used when necessary, particularly for high-risk individuals, and work best when started early. Antibiotics do not kill viruses; they are used only if a secondary bacterial infection develops.